Work Package Leader & Program Manager

Biography

Howard completed his PhD at the University of Queensland in which he demonstrated how quantum trajectory theory could be applied to the problem of quantum feedback, an approach which has now become standard. As a postdoctoral fellow at the University of Auckland (1992-4) he worked mainly on atom optics, pioneering atom laser theory. Subsequently, as an ARC Postdoctoral Fellow he established adaptive quantum measurements as an important research field, in which experiments have since been published in Nature and Science. Then as a QEII Fellow, he developed the theory of non-Markovian quantum trajectories, including “realistic” quantum trajectories for non-ideal measurement devices. As a Federation Fellow he formalized Einstein-Podolosky-Rosen “steering” as a quantum information task and devised the quantum-computing-inspired adaptive algorithm allowing the first demonstration of ab intio phase estimation scaling at the Heisenberg-limit. In 2010, Quantum Measurement and Control by Wiseman and Milburn, the first comprehensive text in this field, was published by Cambridge.

Howard has over 165 refereed journal papers including publications in the Nature suite of journals and 22 in Physical Review Letters. These have garnered more than 4000 citations, with an h-index of 34. He has won the Bragg Medal of the Australian Institute of Physics, the Pawsey Medal of the Australian Academy of Science and the Malcolm Macintosh Medal of the Federal Science Ministry. He was elected as a Fellow of the Australian Academy of Science in 2008 and a Fellow of the American Physical Society in 2011.

Within the Centre, Howard’s Research Program is Quantum Information Theory, defined broadly to include quantum computing, communication, measurement and control. It will provide theory underpinning both quantum communication and quantum computation, and will also exploit related ideas in quantum information, control, and metrology.

Research

Howard’s research has ranged widely in low-energy quantum theory, with an emphasis on addressing conceptual issues. It can be divided roughly into three areas.

Quantum information, measurement, and control

Quantum information theory, broadly conceived, is an approach to quantum theory in which the quantum system is considered as a carrier or processor of information, and/or in which the quantum state is considered as an observer’s state of knowledge about the quantum system. The latter aspect is essential to sophisticated quantum measurement, and measurement-based quantum control, which is why these three areas fit naturally together. Howard’s research includes: conditional evolution and feedback control for open quantum systems in optics and solid-state; adaptive phase metrology; generalized super-selection rules in quantum information processing; formulating and applying EPR-steering as a quantum information task; and quantum computing algorithms.

Open quantum systems and quantum optics theory

An open quantum system is a quantum system continuously interacting with its environment. The theory of this is best understood in quantum optics. In addition to his work on conditional evolution and feedback control for open quantum systems, Howard did pioneering work establishing criteria for an atom laser (or indeed, any laser), and determining the ultimate quantum limit to the laser linewidth. Currently, he is applying quantum open systems and quantum optics theory to quantum information processing technologies.

Fundamental questions in quantum mechanics

Howard has a long-standing interest in quantum fundamentals, mot notably in using weak-values to address paradoxes relating to the momentum-disturbance in which-way experiments, and to motivate Bohmian mechanics in an operational way. He is also working to better understand incompleteness, contextuality, and nonlocality in quantum mechanics.